The past two weeks have been heady ones in New England seafood news, with Legal Seafood’s blacklisted fish dinner at the fore. For anyone who missed it, with the announcement of this dinner, Legal’s has provoked a debate about the ways seafood gets classified as “sustainable.”

They’re serving farmed shrimp from Vietnam, Atlantic cod, and hake, which are all listed “avoid” on the Monterey Bay Aquarium’s Seafood Watch List.

As word of the dinner spread, you could practically feel the reverb from advocacy groups and bloggers. A petition has even been circulated, asking Legal’s to “stop attacking sustainable seafood.”

Was an attack on sustainable seafood the intent? In part, it depends on how you define “sustainable.” Easier said than done, right? Defining sustainability depends on your point of view—it can mean one thing to marine conservationists, another thing to chefs or fishermen, and yet another to big buyers of seafood.

While the blogosphere was erupting over the blacklisted dinner, Massachusetts fishermen were being denied a request to the Commerce Department for emergency aid. Fishermen in this state are struggling to adapt to catch shares, a new regulatory framework that was implemented last spring.

These rules have been contentious. Because the approach caps the amount of fish taken out of specific fishing grounds, as opposed to capping the number of days fishermen could spend at sea, catch shares have been promoted as a sound, quantifiable approach to managing fish populations.

And though it’s been less than a year since catch shares have been implemented, top marine scientists are projecting the end of overfishing and pointing to catch shares as part of the solution.

But despite the upsides, catch shares haven’t caught on with many fishermen—hence the request for aid. One report from the University of Massachusetts-Dartmouth estimates that the new rules have cost the state’s fishing industry $40 million since they were implemented in the spring.

So if the new regulations are helping fish populations rebound, but fishermen are going out of business, where does that leave a definition of sustainability that takes ecological as well as social and economic factors into account?

Parsing sustainable seafood is tricky, as author Paul Greenberg points out in this interview with Salon. With different interpretations held by all of the different stakeholders, it will require a lot of cooperation to identify shared goals that make the pursuit of sustainability one that works at every angle.